New synthetic strategies are needed for the assembly of porous metal titanates and metal chalcogenite‐titania thin films for various energy applications. Here, a new synthetic approach is introduced in which two solvents and two surfactants are used. Both surfactants are necessary to accommodate the desired amount of salt species in the hydrophilic domains of the mesophase. The process is called a molten‐salt‐assisted self‐assembly (MASA) because the salt species are in the molten phase and act as a solvent to assemble the ingredients into a mesostructure and they react with titania to form mesoporous metal titanates during the annealing step. The mesoporous metal titanate (meso‐Zn2TiO4 and meso‐CdTiO3) thin films are reacted under H2S or H2Se gas at room temperature to yield high quality transparent mesoporous metal chalcogenides. The H2Se reaction produces rutile and brookite titania phases together with nanocrystalline metal selenides and H2S reaction of meso‐CdTiO3 yields nanocrystalline anatase and CdS in the spatially confined pore walls. Two different metal salts (zinc nitrate hexahydrate and cadmium nitrate tetrahydrate) are tested to demonstrate the generality of the new assembly process. The meso‐TiO2‐CdSe film shows photoactivity under sunlight.

Developing active, durable, and inexpensive electrocatalysts is critical for hydrogen production to meet ever-growing sustainable energy needs. Nickel sulfides offer significant potential as electrocatalysts for a hydrogen evolution reaction (HER); however, the active phase governing the electrochemical conversion is still under debate. We show that mesoporous thin-film NiS2 synthesized by a novel soft-templating method without post-sulfurization exhibits superior HER activity in alkaline media after a preconditioning step that results in sulfur leaching, amorphization of the surface, and collapse of the mesoporous structure. A comparative analysis with crystalline NiS2 reveals that partial hydroxylation of the under-coordinated Ni sites is responsible for the superior HER activity.

Uniform and homogeneous coating of mesoporous materials with an active (catalytically, photonic, electrical) nanostructure can be very useful for a number of applications. Understanding chemical reactions in a confined space is important in order to design new advanced materials. In this work, we demonstrate that an extensive amount (as high as 53 mol percent) of transition metal salts can be confined between silica walls and two surfactant domains (cetyltrimethylammonium bromide, CTAB, and lauryl ether, C 12 H 25 (OCH 2 CH 2 ) 10 OH, C 12 EO 10 ) as molten salts and then converted into sponge-like mesoporous silicaÀmetal oxides by thermal annealing. This investigation has been carried out using two different salts, namely, zinc nitrate hexahydrate, [Zn(H 2 O) 6 ](NO 3 ) 2 , and cadmium nitrate tetrahydrate, [Cd(H 2 O) 4 ](NO 3 ) 2 , in a broad range of salt concentrations. The ZnO (or CdO) layers are as thin as about ∼1.6 nm and are homogenously coated as crystalline nano-islands over the silica pore walls.

Mesoporous silica metal oxide (ZnO and CdO) thin films have been used as metal ion precursors to produce the first examples of mesoporous silica metal sulfide (meso-SiO(2) @ZnS, meso-SiO(2) @CdS) or silica metal selenide (meso-SiO(2) @ZnSe, meso-SiO(2) @CdSe) thin films, in which the pore walls are made up of silica and metal sulfide or metal selenide nanoflakes, respectively. A gentle chemical etching with a dilute HF solution of the meso-SiO(2) @CdS (or meso-SiO(2) @CdSe) produces mesoporous cadmium sulfide (meso-CdS) (or cadmium selenide, meso-CdSe). Surface modified meso-CdS displays bright blue photoluminescence upon excitation with a UV light. The mesoporous silica metal oxides are formed as metal oxide nanoislands over the silica walls through a self-assembly process of a mixture of metal nitrate salt-two surfactants-silica source followed by calcination step. The reactions, between the H(2) S (or H(2) Se) gas and solid precursors, have been carried out at room temperature and monitored using spectroscopy and microscopy techniques. It has been found that these reactions are: 1) taking place through the diffusion of sulfur or selenium species from the top metal oxide layer to the silica metal oxide interface and 2) slow and can be stopped at any stage to obtain mesoporous silica metal oxide metal sulfide or silica metal oxide metal selenide intermediate thin films.

It has been decades since electrochemical water splitting was proposed as a promising strategy for renewable hydrogen production. Transition-metal dichalcogenides offer cheap, earth-abundant catalyst candidates for the hydrogen evolution reaction (HER). Among those, molybdenum disulfide (MoS 2 ) has been the subject of a vast number of studies, where different approaches such as manipulating the type and number of layers, or density of the intrinsic active sites, and engineering compositional phase and structure have been employed to enhance the electrochemical activity. Herein, we show the HER activities of twodimensional 1T-and 1H-MoS 2 mixed phases with respect to the pure 1H-MoS 2 scale with the 1T phase. The creation of S vacancies in 1H-MoS 2 enhances HER activities. Further enhancement in the activity is achieved by N doping induced by N 2 plasma exposure owing to the formation of a metallic 1T phase and S vacancies. The spectroelectrochemical Raman spectroscopy and ex-situ X-ray photoelectron spectroscopy investigations reveal a gradual phase conversion induced by H adsorption during electrochemical tests. The 1T to 1H phase transformation results in a significant loss in HER activity.